According to financial results released Tuesday, the airline posted a net income of $2.7 billion, excluding special items, last year. That's a $1.1 billion increase over 2012.

Operating revenue improved $474 million in December 2013 compared to December 2012, while traffic increased 2.0 percent on a 2.9 percent increase in capacity.

"Across the board this was an outstanding year, and all credit for these achievements goes to the 78,000 Delta employees worldwide," Delta Air Lines CEO Richard Anderson said in a statement.

Delta also reported a net income of $558 million for the December 2013 quarter, as well as $5 billion of operating cash flow and $2.1 billion of free cash flow last year, allowing the company to reduce its adjusted net debt to $9.4 billion and return $350 million to shareholders.